Carpobrotus edulis

Carpobrotus edulis is native to South Africa. It is also known as ice plant, highway ice plant, pigface or Hottentot fig and in South Africa as the sour fig (suurvy; earlier: hotnotsvy), on account of its edible fruit.

It was previously classified in genus Mesembryanthemum and is sometimes referred to by this name.

Description

Carpobrotus edulis is a creeping, mat-forming succulent species and member of the stone plant family Aizoaceae, one of about 30 species in the genus Carpobrotus.

C. edulis is easily confused with its close relatives, including the more diminutive and less aggressive Carpobrotus chilensis (sea fig), with which it hybridizes readily. C. edulis can, however, be distinguished from most of its relatives by the colour of its flowers. The large (2.5-to-6-inch-diameter (64 to 152 mm)) flowers of C. edulis are yellow or light pink, whereas the smaller, 1.5-to-2.5-inch-diameter (38 to 64 mm) C. chilensis flowers are deep magenta. On the flowers, two of the calyx lobes are longer, extending further than the petals.

The leaves of C. edulis are only very slightly curved and have serrated sides near the tips. ^[1]

In South Africa

Range

The sour fig grows on coastal and inland slopes from Namaqualand in the Northern Cape through the Western Cape to the Eastern Cape. It is often seen as a pioneer in disturbed sites.

Ecology

Leaves are eaten by tortoises. Puff adders and other snakes, such as the Cape cobra, are often found in Carpobrotus clumps, where they ambush the small rodents attracted by the fruits. Flowers are pollinated by solitary bees, honey bees, carpenter bees, and many beetle species. Flowers are eaten by antelopes and baboons. The clumps provide shelter for snails, lizards, and skinks. Fruits are eaten by baboons, rodents, porcupines, antelopes, and people, who also disperse the seeds.^[2]

Growth

Ice plants grow year round, with individual shoot segments growing more than 3 ft (1 m) per year .^{[citation needed]} Ice plants can grow to at least 165 ft (50 m) in diameter. Flowering occurs almost year round, beginning in February in southern California and continuing through fall in northern California, with flowers present for at least a few months in any given population. Seed production is high, with hundreds of seeds produced in each fruit. The fruit is edible. In South Africa the sour fig's ripe fruit are gathered and either eaten fresh or made into a very tart jam.

Invasive species

Carpobrotus edulis has naturalised in many other regions throughout the world, and is an invasive species in several parts, notably Australia, California and the Mediterranean, all of which have similar climates. The ice plant has escaped from cultivation and has become invasive, posing a serious ecological problem by forming vast monospecific zones, lowering biodiversity, and competing directly with several threatened or endangered plant species for nutrients, water, light, and space.^[3]

Removal of plants

Control of ice plants can be attempted by pulling out individual plants by hand, or with the use of earth-moving machinery such as a skid-steer or tractor, though it is necessary to remove buried stems, and mulch the soil to prevent re-establishment. For chemical control, glyphosate herbicides are used. Because of the high water content of shoot tissues, burning of live or dead plants is not a useful method of control or disposal.

Mediterranean

On the Mediterranean coast, Carpobrotus has spread out rapidly and now parts of the coastline are completely covered by this invasive species. Moreover, another invasive species, the black rat, has been shown to enhance the spreading of the ice plant through its feces.^[4] As the ice plant represents a food resource for the rat, both benefit from each other (invasive mutualism).

New Zealand

In New Zealand C. edulis and its hybrids are classed as unwanted organisms and are listed on the National Pest Plant Accord.^[5]

California

Although it may have arrived by ship as early as the 16th century,^[6] C. edulis was actively introduced in the early 1900s to stabilize dunes^[6] and soil along railroad tracks; it was later put to use by Caltrans for similar purposes.^[6] Thousands of acres were planted in California until the 1970s. It easily spreads by seed (hundreds per fruit) and from segmentation (any shoot segment can produce roots). Its succulent foliage, bright magenta or yellow flowers, and resistance to some harsh coastal climatic conditions (salt) have also made it a favored garden plant. The ice plant was, for several decades, widely promoted as an ornamental plant, and it is still available at some nurseries. Ice plant foliage can turn a vibrant red to yellow in color. Despite its use as a soil stabilizer, it actually exacerbates and speeds up coastal erosion. It holds great masses of water in its leaves, and its roots are very shallow. In the rainy season, the added weight on unstable sandstone slopes and dunes increases the chances of slope collapse and landslides.

The ice plant is still abundant along highways, beaches, on military bases, and in other public and private landscapes. It spreads beyond landscape plantings and has invaded foredune, dune scrub, coastal bluff scrub, coastal prairie, and, most recently, maritime chaparral communities. In California, the ice plant is found in coastal habitats from north of Eureka, south at least as far as Rosarito in Baja California. It is intolerant of frost, and is not found far inland or at elevations greater than about 500 ft (150 m).

Cultivation

It needs well-drained soil, a sunny position, and room to spread. It is an excellent evergreen, drought- and wind-resistant groundcover; it can be planted on flat, sandy ground, on loose sand dunes, lime-rich and brackish soils, and gravelly gardens, as well as in containers, rockeries, and embankments, and will cascade over terrace walls.

Uses

Its leaves are edible, as are its fruit, as with some other members of the Aizoaceae family.

Chemistry

Rutin, neohesperidin, hyperoside, catechin and ferulic acid can be found in C. edulis, and contribute to the antibacterial^[7] and antioxidant^[8] properties of the plant. It also contains procyanidins and propelargonidins.^[9]

References

External links

Wikimedia Commons has media related to Carpobrotus edulis.

• USDA Profile
• IPNI Listing
• Carpobrotus edulis at the Institute of Pacific Islands Forestry
• Kew Plant List
• Calflora invasive plants
• Plantzafrica